1. Field of the Invention
The present invention relates generally to a development system for use in image forming apparatuses, such as copying machines, printers and the like. The development system is adapted to develop an electrostatic latent image formed on an image bearing body and more particularly, arranged such that a developer transport member carries thereon a toner to a development region opposite to the image bearing body for development of the image. A toner regulating member bears against the surface of the developer transport member for regulating the amount of toner carried by the developer transport member and also for triboelectrically charging the toner supplied to the development region.
2. Description of the Related Art
Conventionally, the image forming apparatuses, such as copiers, printers and the like, have employed various types of development systems for developing the electrostatic latent image formed on the image bearing body.
The development systems typically known in the art include a development system utilizing a two-component type developer comprising a magnetic carrier and a toner and a development system utilizing a one-component type developer containing no magnetic carrier.
The most common development system utilizing the one-component type developer is arranged such that the developer transport member carries thereon the toner to the development region opposite to the image bearing body for development of the image while the toner regulating member bears against the surface of the developer transport member for regulating the amount of toner carried by the developer transport member and also for triboelectrically charging the toner supplied to the development region.
Unfortunately, in the arrangement wherein the toner regulating member bears against the surface of the developer transport member for regulation of the amount of toner carried by the developer transport member, the toner becomes fixed to the developer transport member, forming a toner film thereon. Hence, an uneven amount of toner is supplied by the developer transport member. This causes a resultant image to suffer irregularities such as density variation.
If the developer transport member has too small roughness on the surface thereof, a reduced amount of toner is carried by the developer transport member. If the reduced amount of toner on the developer transport member is regulated by the toner regulating member, the toner is excessively charged. This causes the resultant image to suffer an insufficient image density or density variation, although the production of an image with defects such as all over fog is avoided.
On the other hand, if the developer transport member has too great roughness on the surface thereof, the developer transport member carries thereon an excessive amount of toner. If the excessive amount of toner on the developer transport member is regulated by the toner regulating member, the toner fails to be adequately charged. This results in an image containing fog all over or an image with toner particles scattered around characters.
Proposed solutions to the above problems include development systems wherein a developer transport member is provided with a layer of specific fine particles bonded to the surface thereof that also contains a nickel coating electrodeposited on the surface of the layer of fine particles, and development systems wherein a surface layer comprising a binder resin containing specific fine particles dispersed therein is laid over the developer transport member (see, for example, Japanese Unexamined Patent Publication No.7(1995)-306586), and the like.
In the developer transport member that contains the layer of fine particles bonded to the surface thereof and further contains the nickel coating electrodeposited on the fine particles, or the developer transport member that contains a surface layer comprising binder resin with fine particles dispersed therein, the fine particles are not adequately exposed to the surface of the developer transport member. This results in a failure of imparting a uniform roughness to the surface of the developer transport member. Thus making it difficult for the toner regulating member to suitably regulate the amount of toner on the developer transport member or to adequately charge the toner, particularly when high speed image development is performed. Consequently, the resultant images still suffer irregularities such as density variation, allover fog and the like. There also exists a problem of poor reproducibility of fine lines and dots.